The present invention is directed to novel polymers containing a branched/block copolymer structure, which is useful for treatment of keratinous substrates, especially to cosmetic compositions, such as hair sprays, hair conditioners, hair setting lotions, creams, and the like, which incorporate the polymers. The polymers provide the cosmetic compositions with greater holding power, less flaking, and better ability to stylize than conventional polymers used in hair and similar cosmetic preparations.
Both natural and synthetic polymers, usually incorporated into an aqueous or an aqueous/alcoholic solution, are in current use as hair lacquers, hair-setting lotions, and the like. The function of such polymers is to impart xe2x80x9cbodyxe2x80x9d and holding power to the hair.
At the present time, the principal polymers or polymers employed in hair sprays, setting lotions, and hair conditioners include polyvinyl pyrrolidone (PVP) homopolymers and copolymers, half esters of polyvinyl ethers-maleic anhydride, polyvinyl acetate-crotonic acid co- and terpolymers, half esters of ethylene-maleic anhydride, acrylates and others.
With the exception of vinyl pyrrolidone homopolymers, conventionally employed synthetic polymers and polymers used in hair sprays, and the like, tend to impart excessive stiffness to the hair, causing an unnatural look. In addition, incorporation of such synthetic polymers or polymers into hair care compositions sometimes leads to excessive flaking, thereby making the compositions unsatisfactory from a commercial standpoint.
Although polyvinyl pyrrolidone homopolymers and copolymers provide a more natural look in that they are free from some of the disadvantages of other commercially available products, they tend to provide less satisfactory holding of the hair at high humidity levels. Typical hair styling polymers are random copolymers which are prepared by polymerizing two or more hydrophilic, anionic, cationic, or hydrophobic monomers, such as acrylic or vinyl monomers. The backbone of the resulting polymer is typically composed of a statistically random distribution of all the monomers. The ratio of these monomers is selected in such a way as to obtain a resin with a certain hydrophilic and hydrophobic balance.
The hydrophobic monomers generally provide better hairstyle retention at high humidity levels. Polymers, in which hydrophobic monomers predominate heavily, however, have poor solubility in water-ethanol mixtures, are not readily washable from the hair, and tend to flake and feel plastic-like on the hair. They are therefore unsuited to use in hair styling formulations.
On the other hand, polymers with high levels of hydrophilic groups have good solubility in water/ethanol mixtures and are washable from the hair. However, they are generally too sensitive to moisture, becoming tacky, and therefore do not hold a hairstyle under conditions of high humidity. U.S. Pat. No. 3,954,960 to Valan, for example, discloses a random copolymer of purely hydrophilic monomers. This is a film forming resin of a quatemized copolymer of vinyl pyrrolidone and a copolymerizable vinyl monomer such as a di-lower alkyl alkyaminoalkyl (or hydroxy alkyl)acrylate or methacrylate. Quaternized polymers of polyvinyl pyrrolidone, however, tend to be highly moisture sensitive and have overall poor performance in hairstyle retention and tack.
Accordingly, it is desirable to build a resin with a balance of hydrophilic and hydrophobic groups to achieve a combination of performance properties, such as style retention at high humidity, tack, hardness, flaking, washability from the hair, and other subjective performance attributes.
A typical example of a random copolymer having a hydrophilic/hydrophobic balance is disclosed in U.S. Pat. No. 3,914,403 to Valan. Valan discloses a film-forming resin formed from polyvinyl pyrrolidone, vinyl acetate, and a cationic monomer. The polyvinyl pyrrolidone and the cationic groups form the hydrophilic portion of the resin, while vinyl acetate provides the hydrophobic portion. By varying the ratio of polyvinyl pyrrolidone to vinyl acetate, water soluble or water insoluble polymers are obtained. The highly water soluble polymers tend to have poor hair style retention at high humidity, whereas the highly insoluble ones are likely to be un-washable and too plastic-like.
U.S. Pat. No. 3,925,542 to Viout, et al. and U.S. Pat. No. 5,196,495 to Chuang, et al. disclose additional examples of random copolymers with various hydrophilic/hydrophobic balances. Uses for the copolymers include aerosols, lacquers, non-aerosol hair sprays, hair setting creams, and setting lotions.
U.S. Pat. No. 4,007,005 to Patel discloses a hair setting resin based on a random copolymer of a reactive polyamide epichlorohydrin and polyvinyl pyrrolidone. The copolymer provides long style retention at high humidity. However, the reactive polymers are toxic and lack washability from the hair when used as aerosols, non-aerosol hair sprays and setting lotions.
Due to environmental regulations controlling the emission of volatile organic compounds (VOC""s) into the atmosphere, VOC emissions have been restricted to 80% by weight of the hair styling formulation in some states, with further restrictions to 55% anticipated. To meet the regulations, reduced VOC hair styling formulations are being developed. Water is substituted for part or all of the organic solvents conventionally used in such formulations. U.S. Pat. No. 5,565,193 to Midha, et al. discloses a random copolymer hairstyling resin primarily formed from monomers such as n-butyl acrylate (the hydrophobic component), and acrylic acid, the (hydrophilic component), grafted with siloxane to balance the properties and to render the resin suitable for formulation in an 80% VOC composition. However, such polymers tend to become too soft and produce negative beading on the hair in low VOC formulations.
U.S. Pat. No. 5,620,683 to Tong, et al. discloses a resin comprising a random copolymer of n-alkyl acrylamide (the hydrophobic component) and acrylic acid (the hydrophilic component). Although the polymers are said to be suited to use in low VOC formulations, such polymers tend to be insoluble in water. Rather, they form a slurry in water and ethanol blends. Only upon adding the liquefied propellant gas, such as dimethyl ether, to the aerosol cans, does the resin dissolve. Preparing a slurry and pumping it into the aerosol cans is impractical for most purposes. In addition, because the resin is insoluble in water, it may prove difficult to wash from the hair.
U.S. Pat. No. 5,599,524 to Morawski, et al. discloses a hair spray composition in a formulation having 80% VOC""s, or less. A defoaming agent is added to a conventional hair resin to reduce surface tension and to eliminate foaming of aerosol and non-aerosol hair sprays. The composition does not provide an improvement in flaking, fly away, or humidity resistance over conventional formulations.
U.S. Pat. No. 5,501,851 to Mudge, et al. discloses a random copolymer of butyl acrylate, methyl methacrylate, hydroxyethyl acrylate, and methacrylic acid for low VOC formulations. The polymer is dispersed in an emulsion to render it later removable with a shampoo.
The present invention provides for new and improved block/branched copolymers and hair treatment compositions incorporating the copolymers, which overcome the above-referenced problems, and others.